Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Mazda’s rotary engine in the age of the electric car

nippon.com

Post reply on HN
Print view View original

61–70 of 295 posts

Re: Mazda’s rotary engine in the age of the electric car

#61

Post by LarsDu88 »

jdblair wrote: post #46
shanusmagnus wrote: post #32

What was the purpose of using the rotary engine in the first place, for ICE cars? From the comments it seems it's maybe lighter for a given power output. Is that it, other than just the novelty of it?

Lighter and mechanically simpler were the selling points. Poor fuel efficiency and trouble with the seals were the downsides. My uncle had an RX-7 back in the 80s when I was a kid. I remember when it was idling I could see the exhaust puffing, in pulses. It only had a single combustion chamber after all.

It's mechanically simpler until the apex seals blow out. Then you are fucked

Re: Mazda’s rotary engine in the age of the electric car

#62

Post by userbinator »

iamthirsty wrote: post #31
coryrc wrote: post #28

Earlier quoted context omitted.

Then you may as well use a gas turbine, which is pretty much better in every way that matters for generating purposes.

Except extremely complex and usually hard to repair and inefficiently sized for a consumer car.

Actually far simpler than a piston engine; the fuel consumption and high production cost was what made them become extinct.

https://en.wikipedia.org/wiki/Chrysler_Turbine_Car

Re: Mazda’s rotary engine in the age of the electric car

#63

Post by jeffbee »

aidenn0 wrote: post #53
dragontamer wrote: post #47

A good article. It barely addresses the elephant in the room however: The Toyota Prius and its Atkinson engine. The Atkinson engine is 99% the same as a regular engine (aka: Otto cycle), except the timing is different. Instead of closing the valves when the piston+cylinder is full of gasoline+air mix... the Atkinson engine waits a bit and "leaks" some gasoline+air back out before closing the intake valve, effectively…

I am mildly annoyed that Toyota calls late intake valve closing (LIVC) an "Atkinson-cycle" Atkinson made 3 engines none of which are anything like a 4-stroke with LIVC. The closest is perhaps his two-stroke engine, which kept the exhaust valve closed during the power stroke and open for part of the compression stroke. The Miller-cycle is much closer to what the Prius uses than anything Atkinson made; it was a traditi…

And, of course, Mazda had been selling LIVC engines for years before the Prius appeared. Like all of Mazda's other weird engines they were expensive, bad, and unreliable.

Re: Mazda’s rotary engine in the age of the electric car

#64

Post by mrighele »

coryrc wrote: post #28
sethhochberg wrote: post #16

Earlier quoted context omitted.

They have a pretty narrow power band (produce efficient max power at a small range of RPMs) which always somewhat limited their use for normal ICE cars, but is a pretty workable constraint for an electrical generator. So you have compact size, good power to weight ratio, and power limitations that don't really matter for range extender purposes. Lots of potential. I can't find the article right now, but I'd swear I r…

Then you may as well use a gas turbine, which is pretty much better in every way that matters for generating purposes.

If all you need is power generation, use a nuclear reactor. Time to bring back the Ford Nucleon ! [1]

Comes with daily free health checkup (in form of an X-Ray).

[1] https://en.wikipedia.org/wiki/Ford_Nucleon

Re: Mazda’s rotary engine in the age of the electric car

#65

Post by mrighele »

WalterBright wrote: post #38
coryrc wrote: post #28

Earlier quoted context omitted.

Then you may as well use a gas turbine, which is pretty much better in every way that matters for generating purposes.

Gas turbine cars have been built, but they tend to set anyone on fire if they walk behind the car. https://bandimere.com/previewing-the-brakes-plus-jet-car-nat...

Some models do, some others do not: https://www.youtube.com/watch?v=b2A5ijU3Ivs, https://www.youtube.com/watch?v=CdCudNSti_Q

Re: Mazda’s rotary engine in the age of the electric car

#66

Post by ksec »

skellera wrote: post #8
486sx33 wrote: post #2

Does it produce more low end torque verses a traditional gasoline combustion engine? If not then why is it better suited for electrical generation? Is it more efficient with less load? The article mostly makes it sound like Mazda just loves the wankle and wants to find any possibly way to bring it back - even though it has “high” emissions… so coupling it with a hybrid electric motor makes it happen.. That can’t be t…

I don’t understand why Mazda doesn’t just make a drift-tuned electric car. You could do amazing stuff with software focused on that driving style. A true electric successor to the RX-7 would capture so much attention.

>A true electric successor to the RX-7 would capture so much attention.

Not entirely sure that would be the case even with a Red Sun label on it.

Re: Mazda’s rotary engine in the age of the electric car

#67

Post by Electricniko »

deelowe wrote: post #58
calfuris wrote: post #51

Earlier quoted context omitted.

The trick is having a large buffer, so that typically the engine can operate at the point with the best specific fuel consumption or shut down entirely. Getting energy from the engine to the wheels is less efficient than a mechanical transmission, but the increased average efficiency of the engine can more than offset that.

Still seems like a traditional hybrid would be more efficient. I'm not sure what's gained by removing the mechanical coupling altogether (other than cost/reliability).

Honda has an interesting solution in their latest gen hybrids, where the electric motors power the wheels at lower speeds, the combustion engine runs at its optimum RPMs as a generator while the electric motors are working, and at higher speeds a clutch activates that changes the coupling so that the combustion engine directly drives the wheels.

Re: Mazda’s rotary engine in the age of the electric car

#69

Post by explorigin »

Projectiboga wrote: post #13

I was always impressed by this engine in my childhood, but it never really caught on. Here is a variation I've seen on the internet, i'm not sure how practible it would be. https://arstechnica.com/cars/2023/11/this-inside-out-design-...

https://www.youtube.com/watch?v=X5UOqZn43gY It has longevity-issues due to an internal roller bearing on the main shaft.

Re: Mazda’s rotary engine in the age of the electric car

#70

Post by kyleee »

userbinator wrote: post #62
iamthirsty wrote: post #31

Earlier quoted context omitted.

Except extremely complex and usually hard to repair and inefficiently sized for a consumer car.

Actually far simpler than a piston engine; the fuel consumption and high production cost was what made them become extinct. https://en.wikipedia.org/wiki/Chrysler_Turbine_Car

Of course Jay Leno has one; not sure if he’s featured it on his youtube channel (I don’t recall seeing it). Awesome
Post reply on HN